Purpose:
Early stages of diabetic retinopathy are characterized by inflammatory changes. The role of several endogenous anti-inflammatory molecules in this disease is unknown. We aimed at evaluating chronologically the expression of A1AT in the retina of diabetic rats.

Methods:
Four groups of five male Wistar rats with a weight of 200g were treated with an IP injection of 45mg/kg of streptozotocin (STZ). Animals with glycemia levels and a glucose tolerance curve above 200 mg/dl were included in the study. Rats were sacrificed at 12, 16, 20 and 24 weeks of diabetes. Cross sections of retinas were analyzed by immunohistochemistry and western blot (WB) using a primary antibody against A1AT at the different time points. For comparison purposes we also included GFAP, a known marker of retinal stress.

Results:
Retinas of diabetic animals showed a positive immunoreactivity of A1AT in the outer and inner plexiform layers. Staining was seen in small vessels. A1AT expression on WB was significantly higher at 24 weeks compared to that found at 12, 16, and 20 weeks. GFAP immunoreactivity was observed in the fiber layer and its profile of protein expression showed a peak at 20 weeks.

Conclusions:
A longitudinal increased expression of A1AT in the retina of diabetic animals and a positive correlation with GFAP suggests a role of A1AT in the disease process. These findings might contribute to better understand the inflammatory mechanisms in diabetic retinopathy.